Due to the quick development in mobile communication technology in recent years, light weight, low profile and compactness have become the most important factors in designing current mobile communication devices. Accordingly, the antenna for compact mobile communication devices must also satisfy the requirements of small size, planar structure, and multiband operation. Both U.S. Pat. No. 7,209,087 B2 entitled “Mobile Phone Antenna” and U.S. Pat. No. 7,471,249 B2 entitled “EMC Metal-Plate Antenna and a Communication System Using the Same” disclose a mobile phone antenna that occupies a three-dimensional space. However, the antenna with three-dimensional design usually shows a big volume and still may not fully cover the requirements for five-band wireless wide area network (WWAN) operation of GSM850/900/1800/1900/UMTS.
In this invention, this problem is solved by developing a monopole slot antenna particularly suitable for use in a folder-type mobile communication device or a mobile communication device having an upper cover. The monopole slot antenna according to the present invention is a planar design to occupy only a small area less than 10×40 mm2, and has a simple structure that can be easily printed or etched on the system circuit board of the mobile communication device at low cost; in addition, the monopole slot antenna of the present invention is capable of five-band WWAN operation in the GSM850 (824˜894 MHz), GSM900 (880˜960 MHz), GSM1800 (1710˜1880 MHz), GSM1900 (1850˜1990 MHz), and UMTS (1920˜2170 MHz) bands.